A single star (SS) type network system 110 as shown in FIG. 1(a) is a type of optical access network in which optical fiber is used for data transmission in the access line domain. In the SS type network system 110, communications between an optical line terminal (OLT) 111 and an optical network unit (ONU) 115 take up the whole bandwidth of optical fiber 112.
Another mode of optical access network is a passive optical network (PON) type network system 120 as shown in FIG. 1(b). In the PON type network system 120, the bandwidth of optical fiber 140 between an OLT 130 located at a telephone station or the like and an optical splitter 150, which is a branch point for optical fibers to optical network units (ONUs) 170 located at a plurality of subscriber homes is shared by the ONUs 170.
A media converter is a typical equipment used to transmit data in a point-to-point (hereinafter also referred to as “P2P” as appropriate) transmission scheme in the SS type network system 110.
Recently, a transmission scheme using Ethernet (registered trademark) standardized by the IEEE 802 Committee, called “EFM” (Ethernet (registered trademark) in the First Mile), has been finding use in the access line domain. An example of an EFM transmission scheme established by IEEE is “1000BASE-BX10”, which is a P2P transmission scheme capable of realizing a transmission speed of 1 Gbps.
Also, there are “1000BASE-PX10” and long-distance version “1000BASE-PX20” as point-to-multipoint transmission schemes in the PON type network system 120 capable of realizing the transmission speed of 1 Gbps. The “1000BASE-PX10” and “1000BASE-PX20” are commonly known as “EPON”, or “Ethernet (registered trademark) Passive Optical Network”.
[Patent Citation 1] Japanese Patent Application Publication No. 2003-332991